題目：Reanalysis of single-fiber pull-out  test

報告人：卿海教授（南京航空航天大學航空宇航學院航空航天交叉研究院）

時間：2017年3月29日10:10

地點：A18-209會議室

主辦單位：科協、航空宇航學院、航空航天交叉研究院、機械結構力學及控制國家重點實驗室

報告人簡介：

卿海，男，教授，博士生導師，1998年9月-2002年7月，西安交通大學，工程力學系，本科生；2002年9月-2007年7月，清華大學固體力學，博士研究生(導師楊衛院士)；2007年11月-2011年2月，丹麥技術大學，博士后；2011年3月-2014年6月，西門子風能公司(丹麥)，風機復合材料葉片高級研發工程師；2014年7月起，南京航空航天大學，教授。2013年受聘“江蘇特聘教授”；2016年入選江蘇省六大人才高峰。長期從事先進材料與結構的研究工作，尤其應用計算固體力學從事科學研究與工業產品研發工作。在西門子工作期間，作為項目主管、項目首席結構工程師及結構工程師參與完成西門子風能公司的多個風機復合材料葉片相關的技術攻關項目。

報告摘要：

    A new theoretical model is developed in  order to predict the stress transfer during the quasistatic single-fibre pullout  process. The theoretical approach retains all relevant stress and strain  components, and satisfies exactly the interfacial continuity conditions and all  the stress boundary conditions. For both matrix and fibre, the equilibrium  equations along radial direction are satisfied strictly, while the equilibrium  equations along axial direction are satisfied in the integral forms. Three  normal stress-strain relationships are strictly satisfied, while the radial  displacement gradient with respect to the axial direction is neglected for shear  stress-strain relationship. The general solutions of the axial and radial  displacements in both fibre and matrix are obtained in explicit forms. In the  debonded region, a modified Coulomb’s friction law, in which the frictional  coefficient is a decreasing function of pullout rate, is applied to determine  the interfacial frictional stress. A theoretical analysis for the single-fiber  pullout with unload process is presented based on the energy-based debonding  criterion and the modified analysis of stress transfer between fiber and matrix.  The relationship between the applied stress and the interfacial relative  displacement is expressed as a function of the radial residual thermal stress,  fiber pullout rate and volume content as well as the length of reverse  frictional sliding. The influence of fiber pullout rate on interfacial  frictional coefficient is also taken into consideration. The theoretical results  from present model agree well with the results from finite element model. The  calculation results show that the applied stress result in further debonding  increases with the increase of the radial residual thermal stress and the fiber  volume content and the decrease of the fiber pull-out rate. There is a drop for  the applied stress when the interface debonding close to the model length and  the drops of short models are larger than those of long models. Under different  conditions, the model length almost has no influence on the debonding and  reverse sliding in unloading processes at the initial debonding  region.